Running hot

[kenji]

I've had my 2015 fj09 for 3 years now and recently it started running warmer than usual. I've not done an ECU flash or any performance mods, but over the past several weeks it's been running around 220F + on morning rides, ambient temps have been on the 90's. The fan does work and it's on when I've been riding a while, there are no restrictions around the radiator, other than a radiator guard that's been there since day one. 

I couldn't find any reason why it would run hot, so as a first step, I changed the coolant and flushed out the old stuff with distilled water and refilled it. Today the running temperature seems to be like it was before, around 180F and about 200F when stopped. There didn't seem to be anything wrong with the coolant that I drained out, but I'm wondering if the thermostat may be intermittently beginning to fail. The thermostat is a whole assembly, not just a little thing like on a car, so I'm reluctant to start throwing $50 parts at the problem. 

Just curious if anyone else has come across this or knows of it.

Edited September 6, 2019 by kenji
misspelled word

[jsp]

     Over the years I've found a couple of useful tips for a cool running bike. At least every 6 month spend sometime cleaning the radiator, bugs, grease and grime, road sh!t reduces air flow. Spray on some biodegradable degreaser, from both the front and the back of the radiator. Simple Green or Oil Eater is what I use. Let it sit for a good 10 minutes and spray it again and let it sit again. Then flush it out. That usually does the trick. Some bikes have a marginal cooling system. On those, when I flush and change the coolant I change the mix. I live in the San Diego area so freezing is never an issue. I run 1/3 coolant, 2/3 distilled water plus 1 ounce of Water Wetter. Coolant gives you protection from freezing, a higher boiling point, helps prevent corrosion and lube the water pump, but has less cooling capacity the straight water. Normal is 50%/ 50%. I go to 33%/67%. I hope that helps.

john

[kenji]

Thanks for the tips! The coolant I had may have been more than 50%, because the fresh coolant seems to be working well. I'll try diluting it a bit with some distilled water and add some Water Wetter. 

[bugie]

The temperatures you mention are normal. My GT is constantly between 95-105 celsius in summer when ambient temperature is around 30 degrees. In winter when ambient temperature is 10 degrees celsius, the bike will be at the 80 degree celsius mark

[v1nn1e]

I was riding home recently and the temps here are getting cooler, under 10 celsius, maybe down to 5.

As it was wet and I was tired, I decided not to filter and so spent a minute or two here and there sitting in traffic, but I was still surprised when I heard the fan come on and the temperature up at 105. Normal open road temp seems to be pretty much always in the low 70 celsius. The rest of the journey was urban and whilst I got below 100 and the fan turned off, after a couple of miles and getting home the temp was still up in the 80's.

I was surprised how quickly the temperature builds, even in cold temperatures. I've not ridden much in summer temperatures although I certainly noticed the fan come on a couple of times. I'll keep an eye on it next summer.